
Caesar suffered from epilepsy, and is recorded by Plutarch to have had a seizure right before battle. Caesar often tried to cover this weakness up, but strange fits of migraine, as well as loss of consciousness and seizure, were on record. It is said that his first epileptic attack occurred in Cordoba. Caesar used warfare as a tonic for his health, to make his body strong to fight the epilepsy.
Source:
http://everything2.com/title/Julius+Caesar%2527s+illness